Here's another quatrain authored by the young Clark Ashton Smith that was unpublished during his lifetime:
Time holds the keys of all eternity
Its warder grim is he;
The Past he shuts and locks forevermore,
Then opes the Future's door.
This is a simple little poem, but presents an appealing rendition of the inexorable march of time. The personification of Time as a "warder grim" with his set of keys is both effective and somewhat dour at the same time.